Polyvinyl acetal resin sheets containing di-isoamyl sulphone



Patented Nov, 12, 1940 PATENT OFF-ICE POLYVINYL ACETAL RESIN SHEETS CON- TAINING DI-ISOAMYL SULPHONE Donald R. Swan, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing.

Application December 13, 1939, Serial No. 308,956

1 Claim. (01. 260-36) One object of my invention is to produce com 5 positions of matter which can be made into permanently transparent sheets suitable for use in laminated, shatter-proof glass. Another object is to produce compositions which can be rolled, extruded, molded, or otherwise worked into rela tively thick sheets and massive plastics. Other objects willhereinafter appear.

I have discovered that di-isoamyl sulphone is a useful plasticizer for certain polyvinyl acetal resins, namely, the polyvinyl acetaldehyde and butyraldehyde acetal resins. Moreover, I have discovered that when 40 or more: parts ofdi-isoamyl sulphone isused with 100 parts of polyvinyl butyraldehyde acetal resin, an unusual and remarkable effect is obtained which I may call elasticizing. That is to say, a sheet of polyvinyl butyraldehyde acetal resin containing about 40 or more parts of ,di-isoamyl sulphone per 100 parts of resin possesses the property which, in,

the rubber industry, is known as nerve"; namely, the property of stretching to a considerable extent when tension is exerted upon it, and returning to its original dimensions when the tension is released. This property renders such sheets, which I shall call rubbery sheets, particularly useful in the manufacture of shatterproof glass.

Sheets for use in laminated glass may be made by dissolving the polyvinyl butyraldehyde' acetal resin and the di-isoamyl sulphone in a suitable volatilesolvent or solvent mixture, such-for instance, as acetone, methanol, acetone-methanol mixtures, ethylene chloride-methanol mixtures, etc., about 300 to 500 or'more parts of the solvent or solvent mixture being used per 100,parts of 40 the resin. The solution is then cast as a sheet, the volatile solvent evaporated; and the sheet stripped from the casting surface.

Sheets for use in laminated glass may also be made without the use of volatile solvent by extrusion, for example, in the manner set forth in application Serial No. 147,934 of John S. Kimble and Ernest C. Blackard, filed June 12, 1937. 5 For example, 40 or more parts of di-isoamyl sulphone and 100 parts of a polyvinyl butyraldehyde acetal resin may be mixed in a suitable, jacketed mixer at a low temperature, for example 10 0., and the mixture may then be m worked on hot rolls, in the manner described in U. S. Patent 2,048,686 of F. R. Conklin, until complete homogenization has taken place. The mass thus produced may then be extruded through an annular die, and the tube so formed slit to form a sheet.

The polyvinyl acetal resins can be prepared by reacting polyvinyl alcohol with an aldehyde in the presence of an acetal condensation catalyst, e. g., a mineral acid. These resins can also 20 be prepared by simultaneously de-esterifying a polyvinyl aliphatic ester and reacting the deesterification product with an aldehyde in the presence of a de-esterifying catalyst and acetal -condensation catalyst. Miner-a1 acids are cata- 25 lysts for both de-esterification and acetal formation.

Examples of the preparation of polyvinyl butyraldehyde acetal resins may be found in U. S. Patent 2,044,730, Examples 2, 5 and 6; British Patent 466,598, Example 5; French Patent 813,- 303, Example 1; French Patent 813,514, Examples 1, 2, 3 and 4; and British Patent 459,878, Examples 1, 2, 5, 6, 7, 8, 9 and 10.

What I claim as my invention and desire to be secured by Letters Patent of the United States A transparent, rubbery sheet comprising 100, parts of a polyvinyl bdtyraldehyde acetal resin and at least 40 parts, approximately, of di-iso- 4o amyl sulphone.

DONALD R. SWAN. 

